from tkinter import *
root=Tk()
root.title('登录界面')

def hello_call_back():
      pri( "Hello Python", "Hello World")

button = Button(root, text="Hello", command=hello_call_back)
button.pack()
#relx是相对于窗口的x轴的比例，rely是相对于窗口的y轴的比例，anchor是相对于组件的位置
button.place(relx=0.5, rely=0.5, anchor=CENTER)
root.mainloop()
